The idea seems prevalent among men operating small properties in the mining districts of Arizona that the smelters and custom mills do, in many cases, give false returns on ores that are sent in for smelting or treatment. With a view to ascertaining the facts "of the case, the Arizona State Bureau of Mines has conducted an investigation and has found that it would be utterly impractical for any smelter or mill to so falsify its method of sampling as to give low returns and still give the shipper one half of the sample to allow check assays to be made. This bulletin is written with the idea of showing the" small shipper how to sample, so that he may sample his ores before shipment and ascertain the correct value so that he may have a check on the smelter. Smelter methods of sampling are also given, so that the reader may determine for himself, that, owing to the great changes in the routine and the large number of men that would be necessary in any falsifying system, the smelters could not afford to give incorrect returns. 14 p.